Ddos 
Canonical recently released microcode updates for all Ubuntu users who use AMD processors, focusing on the well-known Spectre security flaw. After the vulnerability was discovered by Jann Horn of Google Project Zero earlier this year, the second variant (CVE-2017-5715) described as a derivative injection attack that could be exploited by local attackers to extract sensitive information including kernel memory.
To solve this problem, processor microcode needs to be updated. Canonical today released an upgraded version of amd64-microcode microcode for all Ubuntu versions that use AMD processors, including Ubuntu 18.04 LTS (Bionic Beaver), Ubuntu 17.10 (Artful Aardvark), Ubuntu 16.04 LTS (Xenial Xerus) and Ubuntu 14.04 LTS (Trusty Tahr).
Canonical said that the updated amd64-microcode microcode has updated the microcode of AMD’s 17H series processors. Ubuntu 18.04 LTS must upgrade amd64-microcode – 3.20180524.1~ubuntu0.18.04.1; Ubuntu 17.10 upgrades amd64-microcode – 3.20180524.1 ~ ubuntu0.17.10.1; Ubuntu 16.04 LTS users upgrade amd64-microcode – 3.20180524.1 ~ ubuntu0.16.04.1; after microcode updates need to restart the device.